1. Field of the Invention
The present invention relates to a method of forming a stator coil surface coating layer and a coating material injection device used to form a semiconductive coating layer which are techniques of repairing exfoliation of a semiconductive coating layer formed on the surface of a stator coil of a rotating electrical machine.
2. Description of the Related Art
A semiconductive coating layer is formed on the surface of a stator coil of an air-cooled electric generator, and there is a case where the semiconductive coating layer thus formed is partially vanished due to a voltage, temperature increase, etc. occurring when the electric generator is operated. Aerial discharge during operation occurs at a site at which the semiconductive coating layer is partially vanished and ozone or nitric acid occurs, so that metal is corroded and corrosion products cause decrease of the meg value of a rotator coil. The repair of the semiconductive coating layer has hitherto followed an extensive dismantling work of drawing out the stator coil from a stator core slot, and thus there is a problem that a repairing cost and much time are required.
Furthermore, there has been disclosed a technique of disposing a coil in a slot portion under the state that a tube-shaped member is attached to the side wall of the coil, semiconductive epoxy resin is injected into the tube and then the resin concerned is hardened to firmly support and fix the coil in the slot (for example, see JP-A-2006-180611).
The semiconductive coating layer formed on the surface of the stator coil of the conventional air-cooled electric generator has been partially exfoliated and vanished due to the voltage and the temperature increase occurring during the operation of the electric generator in some cases. When the stator coil is drawn out from the slot of the stator core and repaired, the cost and the time are required.